Lack of benefit of CD34(+) cell selected over non-selected peripheral blood stem cell transplantation in multiple myeloma: results of a single centerstudy

In order to determine the clinical impact of CD34(+) cell selected autologo us transplantation in multiple myeloma (MM), we have performed a retrospect ive case-controlled analysis comparing 21 MM patients receiving high-dose m elphalan and autologous transplantation with CD34(+) peripheral blood stem cells (PBSC) as front-line therapy to 21 control patients receiving unselec ted products. Case matching was performed using the following criteria: age and beta 2-microglobulin at diagnosis and disease status at the time of tr ansplantation. Both cohorts were homogeneous in term of induction treatment and conditioning regimen. Patients were collected for CD34(+) selection af ter priming with G-CSF alone. Significantly fewer CD34(+) cells/kg were inf used to patients in the selected group as compared to patients in the contr ol group: 2.2 (range 0.5-14.3) vs 9.4 (range 1.1-15) (P < 0.001). The media n time to neutrophil recovery greater than or equal to 0.05 x 10(9)/l was 1 0 days for the CD34(+) group and 9.5 days for the control group (P = 0.357) . The median time to platelet recovery greater than or equal to 20 x 10(9)/ l was 9 days for the CD34(+) group and 4.5 days for the control group (P = 0.005). Response rates were comparable in both groups (85.7% in the CD34(+) group vs 90.4% in the control group). At 3 years, event-free survival (32% in the CD34(+) group vs 39% in the control group) and overall survival (85 % in the CD34(+) group vs 79% in the control group) were not significantly different. Finally, use of unselected products dramatically reduced the cos t of the transplantation procedure. This study shows that CD34(+) cell sele cted autologous transplantation is more expensive than transplantation with unselected products and does not improve the clinical outcome of patients with MM.